Okay I'll assume you've downloaded and unzipped both titlewriter files and the menutemplate files
In Shrink
Reduce Target size in preferences by size of menu (Probably about 1 Meg to 4463)
(You may not have to do this as the provided menu templates are very small, and 4464 is already under the 4482 max)
Reauthor the movies normally
Fire up titlewriter
--- Select folder Containing video_ts.ifo
---Click Add Menu
--Select menu Template - In this case probably Menu2Movie
This adds a basic Generic menu to navigate to both movies,with chaptering,and audio selection
Or if you have a menu supporting both movies select that